Pulsation and mass loss in red giant stars

During the final stages of AGB evolution, single red giant stars pulsate and lose large amounts of mass, enriching the interstellar medium in elements such as C, N and s-process species. About 30% of stars are binaries which end their red giant evolution by mass transfer to a binary companion and to the interstellar medium. In this paper, I discuss recent Spitzer measurements of mass loss rates for single AGB stars in the Magellanic Clouds and explore how these mass loss rates depend on luminosity and mass. I also discuss red giants which are currently in the process of interaction with close binary companions and which are near to losing their envelopes by mass transfer.